Ambac M-50 Rebuild w/ pics (MEP-003A)

Mr4btTahoe

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Well... It's been a while. Lol.

The generator has been sitting in my shop since rebuilding the pump but life kept getting in the way of doing anything to it.

Tonight that changed. After over a decade...IMG_20200805_174817782.jpgIMG_20200805_174829218.jpgIMG_20200805_174835524.jpgIMG_20200805_174840473.jpgIMG_20200804_071902635.jpg

Sent from my moto x4 using Tapatalk
 

Mr4btTahoe

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It did fire and run good. Have some parts to track down but the pump seems to be doing great. It was hazing BAD at first but that's to be expected. After the first start, I let it sit for 15-20 minutes and fired it back up for 5 minutes or so and the hazing was already substantially better. Likely dirty/gummy injectors.


 
Last edited:

Chainbreaker

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Nice job, it sounds like its running good.

Anyone with a MEP-003a or -002a with injection pump issues will find this thread quite useful.

Thanks for coming back to share your pump rebuild success with us!
 

DanD

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oklahoma
This has/will help me with the pump rebuild on the mep 002a I'm working on. Just a question on replacing the pump. Where can I find the how to's to replace pump so the timing is correct. understand It is like replacing a distributor and must be set correctly. I've downloaded the rebuild manual and having a little trouble understanding where to set the timing mark on the flywheel.

thanks
 

DanD

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oklahoma
This Ambac PDF should help. I think the info you are looking for begins on pg 4, but you should read all of it from start.
Found what I was looking for. To bad it wont do me any good until I find a new pump. The pump shaft is sheared off just above the plunger tappet where the drive pin goes. Thanks for the link I've printed it off along with the technical manual. All 194 pages.
Now to find either a buildable pump or a reman pump.
Thanks
Dan the radiator man
pump shaft.jpg
 

Mr4btTahoe

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As for installing/timing the pump... put #1 cylinder at TDC on compression. I don't recall what the mark on the flywheel is (there are several.. 1 for TDC and 2 for valve adjustment.). With the #1 @ TDC, there is a small screw on the bottom of the pump flange (bottom with the pump installed.. pointing towards the ground). Remove that screw and insert a 1/8" drill bit shank into the hole. Rotate the pump by hand until the bit drops into a groove. Carefully install the pump. That's it. It sounds more complicated than it is.. but the hardest part is putting the engine at TDC which isn't difficult.

Now when you get a new pump... you'll have to have the proper timing button and such. That's out of my area for sure as there is a procedure to selecting the proper one (if your original isn't right for the new pump).
 

DanD

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oklahoma
One last question. Does the bosch use the same timing button as the ambac? Are they swappable?

just trying to get all the ducks in a row before I buy the new pump.

thanks
 

jmenende

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The big auction site has a listing with 10 of these pumps rebuilt.
 

762luver

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Location
VT
The big auction site has a listing with 10 of these pumps rebuilt.
Can two of the ports be caped off to work with a MEP-002A or are there any internals which are different? The part number on the tag in the picture on the site matches exactly with the tag on my pump.

I've got my current pump in parts on the bench waiting for a rebuild kit and replacement guide plate, but it would be nice to have a spare on the shelf just in case.
 

Mr4btTahoe

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Indiana
Can two of the ports be caped off to work with a MEP-002A or are there any internals which are different? The part number on the tag in the picture on the site matches exactly with the tag on my pump.

I've got my current pump in parts on the bench waiting for a rebuild kit and replacement guide plate, but it would be nice to have a spare on the shelf just in case.
I wouldn't attempt that. Each port is fired at a different time so it won't work.
 

jmenende

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Can two of the ports be caped off to work with a MEP-002A or are there any internals which are different? The part number on the tag in the picture on the site matches exactly with the tag on my pump.

I've got my current pump in parts on the bench waiting for a rebuild kit and replacement guide plate, but it would be nice to have a spare on the shelf just in case.
Yes, you cam cap off those ports.
 

762luver

Member
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Location
VT
When you cap the ports, make sure you remove the brass plugs from your old pump and put them into the ports of the new pump, don't just use the caps, that won't work. The cap doesn't do the sealing, it simply forces the tapered brass plugs into the holes to seal them off.
Thanks Ray, I'd like to think that I would have figured that out by myself. I certainly appreciate the heads up. There are more than one got'cha's with these sets. My biggest one is not running it as often as I should have. My set was 'a runner' previously until i let it sit too long. Now i have the opportunity to get my hands dirty. If I notice any other 'new to me' -002 or -003 folks, I'll be sure to mention my situation such they they can avoid the fun I'm having.
 
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